Apparatus and method for stylet-guided vertebral augmentation

ABSTRACT

A stylet-guided balloon vertebroplasty system, as well as methods for bone augmentation using same are provided. In certain embodiments, a pre-curved stylet with an overlying delivery tube may be used to target an approximately centered target site within a bone structure, facilitating direction thereto of an expandable member useful for creating a cavity that may receive curable material to restore bone height and/or to reinforce the bone structure.

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. §120, this application is a continuation of andclaims priority to and through U.S. patent application Ser. No.14/528,384, filed Oct. 30, 2014, which is a continuation of (i) U.S.patent application Ser. No. 13/483,919, filed May 30, 2012, issued asU.S. Pat. No. 8,894,658, which is a continuation-in-part of U.S. patentapplication Ser. No. 12/615,573, filed Nov. 10, 2009, issued as U.S.Pat. No. 8,226,657; is a continuation-in-part of and claims priority to(ii) U.S. patent application Ser. No. 14/050,017, filed Oct. 9, 2013,issued as U.S. Pat. No. 9,095,393; and is a continuation-in-part of andclaims priority to (iii) U.S. patent application Ser. No. 14/223,064,filed Mar. 24, 2014, which is a continuation-in-part of U.S. patentapplication Ser. No. 13/483,899, filed May 30, 2012, issued as U.S. Pat.No. 8,690,884, each of which is incorporated by reference herein in itsentirety.

TECHNICAL FIELD

Embodiments disclosed herein generally relate to systems and methods forstabilizing bone structures. More particularly, they relate to systemsand methods for stabilizing, and restoring the height of, a bonestructure, such as a vertebral body.

BACKGROUND

Surgical intervention of damaged or compromised bone sites has provenhighly beneficial for patients, including, for example, patients withback pain associated with vertebral damage. The vertebral damage may bedue to injury and/or a degenerative condition such as, for example,aging and/or osteoporosis.

Bones of the human skeletal system include mineralized tissue that maybe generally categorized into two morphological groups: “cortical” boneand “cancellous” bone. Outer walls of all bones are composed of corticalbone, which is a dense, compact bone structure characterized by amicroscopic porosity. Cancellous or “trabecular” bone forms the interiorstructure of bones. Cancellous bone is composed of a lattice ofinterconnected slender rods and plates known by the term “trabeculae”.

During certain bone-related procedures, cancellous bone is supplementedby an injection of a palliative (or curative) material employed tostabilize the trabeculae. For example, superior and inferior vertebraein the spine may be beneficially stabilized by the injection of anappropriate, curable material (e.g., PMMA or other bone cement or bonecurable material). In other procedures, percutaneous injection ofstabilization material into vertebral compression factors, by, forexample, transpedicular or parapedicular approaches, has provenbeneficial in relieving pain and stabilizing damaged bone sites. Suchtechniques are commonly referred to as vertebroplasty.

A conventional vertebroplasty technique for delivering the bonestabilizing material entails placing a cannula with an internal trocarinto the targeted delivery site. The cannula and trocar are used inconjunction to pierce the cutaneous layers of a patient above the hardtissue to be supplemented, then to penetrate the hard cortical bone ofthe vertebra, and finally to traverse into the softer, cancellous boneunderlying the cortical bone. After the assembly is positioned in thecancellous bone, the trocar may be removed, leaving the cannula in theappropriate position for delivery of curable material that willreinforce and solidify the target site.

In some instances, an effectiveness of the procedure may be enhanced byforming a cavity or void within the cancellous bone, and then depositingthe curable material in the cavity. For example, a balloon or otherexpandable device may be initially deployed and then expanded in aparticular vertebroplasty procedure sometimes referred to askyphoplasty. This action, in turn, compresses cancellous bone and othertissue to form a cavity, and may also cause a “height” of the bone toincrease. As a point of reference, vertebroplasty is a common treatmentfor a fractured vertebral body, and the height of a fractured vertebralbody is oftentimes significantly less than a native or natural heightthat existed before vertebral degeneration. It has been postulated thatthe height of a fractured vertebral body may be restored or elevated toa near-normal state when subjected to internal expansion via a balloonor other expandable member. The mechanics of height restoration inconjunction with vertebroplasty stabilization is currently unclear atbest. For example, certain techniques may employ a bipedicular approachin which two balloons are inserted into the vertebral body and inflated,resulting in an increase in height (and the cavity or cavities describedabove).

There exists a need in the medical device field for improved systems andmethods for restoring the height of, and stabilizing, a fracturedvertebral body or other bone structure. In particular, it would bedesirable to provide apparatus and methods to symmetrically provide boneaugmentation that stabilizes a bone structure such as a vertebra, andthat may also provide some height-restoration of said bone structure.

It may be desirable to provide a system and method that providesadvantages with regard to reduced complexity and reduced procedure timewhile maintaining advantages of dual-balloon kyphoplasty and perhapsoffering superior bone-centralization and symmetry of curable materialplacement.

BRIEF SUMMARY

In one aspect, embodiments disclosed herein may include a stylet-guidedballoon-assisted vertebroplasty system, as well as methods for boneaugmentation using same. In certain embodiments, a pre-curved stylet maybe used to target an approximately centered target site within a bonestructure, facilitating direction thereto of an expandable member usefulfor creating a cavity that may receive curable material to restore boneheight and/or to reinforce the bone structure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a curable material delivery and heightrestoration system, using apparatus for bipedicular access;

FIGS. 2A and 2B illustrate use of the system of FIG. 1 in performing aheight restoration and curable material delivery procedure relative to avertebra, with the vertebra being shown from a superior perspective;

FIG. 2C is a lateral view of the vertebral body of FIGS. 2A and 2B;

FIGS. 3A-3B illustrate the system of FIG. 1 in further performing theheight restoration and curable material delivery procedures with abipedicular dual-balloon method;

FIGS. 4A-4H illustrate a system and method for transpedicular orparapedicular access providing stylet-guided, generally centralizedlocation of a cavity/void and curable material placement therein;

FIG. 4I illustrates a pre-curved delivery cannula; and

FIG. 4J illustrates another system method for transpedicular orparapedicular access providing stylet-guided, generally centralizedlocation of a cavity/void and curable material placement therein.

DETAILED DESCRIPTION

Embodiments are described with reference to the drawings in which likeelements generally are referred to by like numerals. The relationshipand functioning of the various elements of the embodiments may better beunderstood by reference to the following detailed description. However,embodiments are not limited to those illustrated in the drawings. Itshould be understood that the drawings are not necessarily to scale, andin certain instances details may have been omitted that are notnecessary for an understanding of embodiments disclosed herein, suchas—for example—conventional fabrication and assembly.

Various embodiments will be described more fully hereinafter. Theinvention is defined by the claims, may be embodied in many differentforms, and should not be construed as limited to the embodiments setforth herein; rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey enablingdisclosure to those skilled in the art. As used in this specificationand the claims, the singular forms “a,” “an,” and “the” include pluralreferents unless the context clearly dictates otherwise. The word“alternatively” and its variants are used inclusively rather thanexclusively (i.e., “X, alternatively, Y” means “X and/or Y” rather than“only X or only Y”) unless otherwise apparent. The term “about” whenused with reference to any volume, dimension, proportion, or otherquantitative value is intended to communicate a definite andidentifiable value within the standard parameters that would beunderstood by one of skill in the art (equivalent to a medical deviceengineer with experience in the field of vertebral augmentation andother cannular devices/systems), and should be interpreted to include atleast any legal equivalents, minor but functionally-insignificantvariants, and including at least mathematically significant figures.

One embodiment of a curable material delivery and height restorationsystem 10 is shown in FIG. 1. The system 10 includes a first deliveryassembly 12 a, a second delivery assembly 12 b, and at least one sourceof curable material 16. The delivery assemblies 12 a, 12 b may besubstantially identical, and each includes a cannula device 18 a, 18 band a cavity-forming device 20 a, 20 b. Details on the variouscomponents are provided below. In general terms, however, the cannuladevices 18 a, 18 b each include an access cannula 22 a, 22 b forinsertion into a bone site of interest in a patient. In the embodimentdepicted in FIG. 1, the bone site of interest is a vertebra 30. Afterthe access cannulas 22 a, 22 b are desirably located relative to thevertebra 30, a portion of each of the cavity-forming devices 20 a, 20 bare delivered to the vertebra 30 via the corresponding access cannula 22a, 22 b, and operated to form cavities. The second cavity-forming device20 b (alternatively the first cavity-forming device 20 a) may beremoved, and the source of curable material 16 connected to the secondcannula 22 b. In this regard, an delivery tube 14 may be employed,extending from the source 16 and through the second cannula 22 b.

Thereafter, the curable material source 16 is operated to delivercurable material to the cavity via the second cannula 22 b and/or thedelivery tube 14. Subsequently, the first cavity-forming device 20 a maybe removed and the curable material source 16 is connected to the firstcannula 22 a (for example, via the delivery tube 14). The curablematerial source 16 is operated to deliver curable material into thecorresponding cavity. With the approaches disclosed herein, the systemsand methods disclosed herein will be able to provide for restore aheight of the vertebra (or other bone site) 30 to a normal ornear-normal state, and the delivered curable material will providedesirable stabilization.

The system 10 may be used for a number of different proceduresincluding, for example, vertebroplasty and other bone augmentationprocedures in which curable material is delivered to a site within bone(e.g., balloon-assisted procedures where a void is created by a balloonrather than by moving a needle and/or by direct displacement viainjection), as well as possibly to remove or aspirate material from asite within bone. The system 10 is highly useful for delivering acurable material in the form of a bone curable material. The phrase“curable material” within the context of the substance that may bedelivered by the systems and methods described herein is intended torefer to materials (e.g., composites, polymers, and the like) that havea fluid or flowable state or phase and a hardened, solid or cured stateor phase.

Curable materials may include, but are not limited to, injectable bonecements (such as polymethylmethacrylate (PMMA) curable bone material),which have a flowable state wherein they may be delivered (e.g.,injected) by a cannula to a site and subsequently cure into hardened,cured material. Other materials such as calcium phosphates, bonein-growth materials, antibiotics, proteins, etc., may be used in placeof, or to augment bone cement (but do not affect an overridingcharacteristic of the resultant formulation having a flowable state anda hardened, solid, or cured state). This would allow the body toreabsorb the curable material and/or improve the clinical outcome basedon the type of filler implant material. Although FIG. 1 illustrates asingle source of curable material 16, in other embodiments, two (ormore) sources may be provided. The sources may contain identical curablematerial compositions; alternatively, the compositions may differ (e.g.,a first source may contain bone cement, while a second source contains amixture of bone cement and bone in-growth material).

As mentioned above, the cannula devices 18 a, 18 b may be substantiallyidentical, and each includes the outer/access cannula 22 a, 22 b. Thecannula 22 a, 22 b is provided to be positioned in (or immediatelyproximate) the target or injection site for delivery of thecorresponding cavity-forming device 20 a, 20 b, as well as curablematerial. The cannula 22 a, 22 b preferably is made of a surgical gradeof stainless steel, but may be made of known equivalent material(s) thatare both biocompatible and substantially non-compliant at the expectedoperating pressures. The cannulas 22 a, 22 b each define a proximalregion 40 a, 40 b, a distal end 42 a, 42 b, and a lumen 44 a, 44 b(referenced generally), respectively, to allow various equipment such asthe cavity-forming device 20 a, 20 b, a delivery tube 14, one or morestylets (not shown here, but discussed and illustrated with reference toembodiments of FIGS. 4A-4H below), and/or other elements, to passtherethrough.

Surrounding the proximal region 40 a, 40 b of the cannula 22 a, 22 b isan handle 46 a, 46 b for manipulating the cannula 22 a, 22 b andconnecting the cannula 22 a, 22 b with one or more of the cavity-formingdevice 20 a, 20 b and/or the delivery tube 14. In some constructions,the cannula device 18 a, 18 b may further include a handle connector 48a, 48 b serving as a proximal end of the corresponding cannula 22 a, 22b. The handle connector 48 a, 48 b may simply be an extension of thecannula 22 a, 22 b. Alternatively, the handle connector 48 a, 48 b mayincorporate features forming part of a locking mechanism component ofthe system 10. For example, the handle connector 48 a, 48 b may includea luer-lock type of connector, but other known connecting mechanism maybe successfully interchanged (e.g., a conventional threaded hole, athreaded locking nut arrangement, etc.). Features of one suitablelocking mechanism are described in U.S. Pat. No. 7,922,690, which isincorporated herein by reference in its entirety.

The cavity-forming devices 20 a, 20 b may be substantially identical andmay assume various forms appropriate for forming a void or cavity withinbone. In this regard, each of the cavity-forming devices 20 a, 20 bincludes an elongate tubular body 60 a, 60 b distally connected to orforming a working end 62 a, 62 b. The elongate body 60 a, 60 b is sizedto be slidably inserted within the lumen 44 a, 44 b of the correspondingcannula 22 a, 22 b, and may include one or more tubes, shafts, etc.,necessary for operation of the corresponding working end 62 a, 62 b.Thereafter, a proximal region 64 a, 64 b of the elongate body 60 a, 60 bmay be connected to or form a cannula connector 66 a, 66 b. The cannulaconnector 66 a, 66 b may assume various forms conducive for selective,rigid attachment to the corresponding handle connector 48 a, 48 b asdescribed above (e.g., the cannula connector 66 a, 66 b and thecorresponding handle connector 48 a, 48 b collectively form a lockingmechanism), and thus may include or contain a luer-lock threadedfitting. Alternatively, the cannula connector 66 a, 66 b may be omitted,and depth markings (not shown) included along an exterior of theproximal region 64 a, 64 b that facilitate desired locating of theworking end 62 a, 62 b relative to the corresponding cannula 22 a, 22 bas described below.

The working end 62 a, 62 b may include one or more componentsappropriate for forming a cavity or void within bone. For example, insome constructions, the working end 62 a, 62 b may include one or moreexpandable or inflatable members (e.g., a single balloon, multipleballoons, a single balloon with two or more discernable inflation zones,etc.) constructed to transition between a contracted (e.g., deflated)state in which the working end/balloon 62 a, 62 b may be passed throughthe corresponding lumen 44 a, 44 b, and an expanded (e.g., inflated)state in which the working end/balloon 62 a, 62 b expands and compactscontacted cancellous bone. In this regard, a size and shape of theworking end/balloon 62 a, 62 b may be predetermined and/or restrainedwith one or more additional components (not shown), such as internaland/or external restraints. In preferred embodiments the workingend/balloon 62 a, 62 b will be structurally robust, able to withstand(e.g., not burst) at expected inflation pressures and when in contactwith bone. Further, the first working end 62 a and the second workingend 62 b may be identical or different.

The working ends/balloons 62 a, 62 b may be exteriorly coated with amaterial configured to resist bonding with the curable material beingdelivered to the vertebra 30. The anti-sticking coating may assumevarious forms as a function of the selected curable material, and insome embodiments is a silicone coating. Other materials exhibitingaversion to bonding with bone cement are also envisioned, for example,polypropylene. In related embodiments, a thin-walled expandable sleeveconstructed of the selected anti-sticking material (e.g., apolypropylene sleeve) may be disposed over the working end/balloon 62 a,62 b. Though not shown, one or both of the cavity-forming devices 20 a,20 b may include a valve or similar component that operates toselectively seal the working end/balloon 62 a, 62 b. The coating mayalso include thermoinsulative properties and/or chemical barrierproperties (e.g., silicone coating) that will protect the cavity-formingdevice(s) during contact with a curable bone cement material such asPMMA, including preventing adhesion and providing thermal protection ofa balloon and/or other coated structure(s) during exothermic curing ofsuch material. As such, those of skill in the art will appreciate thatthe silicone lubricious coating referenced above implicitly providesnumerous advantages with respect to providing a system and method ofdelivering a curable bone cement material (e.g., PMMA) adjacent toand/or contacting a coated expandable member such as a coated (e.g.,silicone-coated) balloon of the type described in U.S. Pat. Nos.8,771,278 and 8,226,657, each to Linderman et al., each of which isincorporated by reference herein.

The cavity-forming devices 20 a, 20 b each further include one or moreadditional components connected or operable through the proximal region64 a, 64 b for actuating the corresponding working end 62 a, 62 b. Byway of one non-limiting example, each of the cavity-forming devices 20a, 20 b may include a source 68 a, 68 b of pressurized fluid (e.g.,contrast medium) for inflating the balloon(s) carried or formed by thecorresponding working end 62 a, 62 b. A hand-held, syringe-type pump maybe used as the pressurized source. In other embodiments, a single one ofthe sources of pressurized fluid 68 a or 68 b may be provided andemployed to inflate both of the working ends/balloons 62 a, 62 bindividually. Appropriate balloon-inflation systems are well known andwill readily be apparent to those of skill in the art.

Where provided, the delivery tube 14 is sized for insertion within thelumens 44 a, 44 b, and defines a distal tip 80 and a proximal section82. As described below, the delivery tube 14 may be employed to delivercurable material to the target site. Thus, the delivery tube 14 has anouter diameter that is smaller than a diameter of the lumens 44 a, 44 b;however, the outer diameter of the delivery tube 14 preferably will notbe so small as to allow curable material to readily travel around theoutside of the delivery tube 14 and back into the corresponding cannula22 a, 22 b.

A cannula connector 84 may be coupled to, or formed by, the proximalsection 82 of the delivery tube 14. The cannula connector 84 is akin tothe cannula connector 66 a, 66 b described above (e.g., combines withthe selected handle connector 48 a, 48 b to form a locking mechanism),and thus may assume any of the forms previously described.Alternatively, the delivery tube 14, where provided, may form depthmarkings (not shown) along the proximal section 82 that facilitatesdesired locating of the distal tip 80 relative to the cannula 22 a, 22 bduring use.

The delivery tube 14 is configured for fluid coupling to the curablematerial source 16. In some embodiments, a portion of the delivery tube14 projects proximally beyond the cannula connector 84, and is fluidlycoupled to the curable material source 16, for example via an injectionconnector 86. Alternatively, auxiliary tubing 88 may be provided withthe curable material source 16, and fluidly connected to the deliverytube 14 via the cannula connector 84. In yet other embodiments, thedelivery tube 14 is omitted, and the curable material source 16connected directly to the handle connector/proximal end 48 a, 48 b(e.g., the auxiliary tube 88 is connected to the connector 48 a, 48 b;or the tubing 88 eliminated and the curable material source 16 (e.g., asyringe) directly coupled to the connector 48 a, 48 b).

The curable material source 16 may assume various forms appropriate fordelivering the desired curable material, and may typically comprise achamber filled with a volume of curable material and employing anysuitable injection system or pumping mechanism to transmit curablematerial out of the chamber and through the delivery tube 14. Typically,a hand injection system is used where a user applies force by hand to aninjector. The force is then translated into pressure on the curablematerial to flow out of the chamber. A motorized system may also be usedto apply force.

Although the system 10 has been described as including the single sourceof curable material 16, in other constructions, a separate source ofcurable material 16 may be provided for each of the delivery assemblies12 a, 12 b. Similarly, two (or more) of the delivery tubes 14 may beincluded. Along these same lines, the system 10 may be configured suchthat the curable material source 16 is directly connected to one or bothof the cavity-forming devices 20 a, 20 b (e.g., the elongate body 60 aof the first cavity-forming device 20 a may form or terminate at anozzle proximate (e.g., distal) the working end 62 a and through withthe curable material may be directly dispensed).

The system 10 and other systems and methods disclosed herein will beuseful in performing a wide variety of height restoration and bonestabilization procedures as part of an overall curable material deliveryprocedure. As such, FIGS. 2A-3B illustrate use of the system 10 inrestoring the height of, and delivering curable material into, a targetsite of a vertebra 100. In general terms, the vertebra 100 includespedicles 102 a, 102 b and a vertebral body 104 defining a vertebral wall106 surrounding bodily material 108 (e.g., cancellous bone, blood,marrow, and soft tissue). The pedicles 102 a, 102 b extend from thevertebral body 104 and surround a vertebral foramen 110. As a point ofreference, systems of the present disclosure may be suitable or readilyadapted by those of skill in the art for accessing a variety of bonesites. Thus, although the vertebra 100 target site is illustrated, it isto be understood that other bone sites may be accessed and treated bythe system 10 (e.g., femur, long bones, ribs, sacrum, etc.).

The first and second cannulas 22 a, 22 b may be employed to form firstand second access paths to first and second target site locations 120 a,120 b. For example, the cannulas 22 a, 22 b are inserted in abipedicular fashion through respective ones of the pedicles 102 a, 102 band into the bodily material 108. The cannulas 22 a, 22 b provide accessto the corresponding target site 120 a, 120 b at the open distal ends 42a, 42 b thereof. One or more stylets (not shown) may be employed toassist in forming/accessing the target sites 120 a, 120 b. For example,a series of differently-sized or configured (e.g., sharpened and blunt)stylets may be successively delivered through the respective cannula 22a, 22 b to form a channel to the target site 120 a, 120 b.Alternatively, or in addition, an outer guide cannula (not shown) may bedeployed to form an access path for subsequent insertion of the cannulas22 a, 22 b.

After the cannulas 22 a, 22 b are positioned within the bodily material108 at the desired target sites 120 a, 120 b, the cavity-forming devices20 a, 20 b are assembled to the corresponding cannula 22 a, 22 b. Forexample, and as shown in greater detail in FIG. 2B, the elongate body 60a, 60 b is slidably inserted within the corresponding cannula 22 a, 22b, with the respective working end 62 a, 62 b being distally advancedtherethrough. More particularly, with configurations in which theworking end 62 a, 62 b is a balloon or other expandable member format,the working end/balloon 62 a, 62 b is transitioned to a contracted state(e.g., deflated) so as to be slidably received through the lumen 44 a,44 b. The elongate body 60 a, 60 b is positioned relative to thecorresponding cannula 22 a, 22 b such that the respective workingend/balloon 62 a, 62 b extends distal the corresponding cannula distalend 42 a, 42 b. For example, where the elongate body 60 a, 60 b mayinclude depth markings as described above, the appropriate depth markingwill be aligned with the corresponding handle connector 48 a, 48 b (FIG.1), thereby ensuring that the working end/balloon 62 a, 62 b is fullydeployed or extended beyond the corresponding cannula distal end 42 a,42 b. In other constructions, upon connection of the cannula connector66 a, 66 b and the corresponding handle connector 48 a, 48 b, theworking end/balloon 62 a, 62 b is distal the corresponding distal end 42a, 42 b and is positioned at the corresponding target site 120 a, 120 b.Placement of the cavity-forming devices 20 a, 20 b may be performedsimultaneously or consecutively.

As a point of reference, FIG. 2C provides a lateral view of thevertebral body 104 in which the first working end/balloon 62 a has beendeployed (and in the contracted state). As shown, the vertebral body 104is fractured (referenced generally at 122) and thus exhibits a fracturedheight H_(F) that is less than a natural or native height H_(N)(designated generally).

With reference to FIG. 3A, the cavity-forming devices 20 a, 20 b areoperated to cause the corresponding working ends/balloons 62 a, 62 b toform first and second cavities or voids 124 a, 124 b, respectively, inthe bodily material 108. For example, the working ends/balloons 62 a, 62b may be expanded (e.g., inflated) substantially simultaneously.Alternatively, with embodiments in which a single inflation source 68 aor 68 b (FIG. 1) is provided, the first working end/balloon 62 a isinflated and then sealed in the expanded or inflated state. Theinflation source 68 a or 68 b is then fluidly connected to the secondworking end/balloon 62 b and operated to cause expansion thereof.Following expansion of the working ends/balloon 62 a, 62 b, the expandedworking ends 62 a, 62 b are both supporting the vertebral body 108. Inthis regard, and as best illustrated in FIG. 3B, expansion of theworking ends/balloons 62 a, 62 b not only forms the cavities 124 a, 124b, but also restores or enhances a height of the fractured vertebralbody 104. More particularly, a restored height H_(R) is established thatbeneficially approximates the natural height H_(N). The restored heightH_(R) may be the same as, slightly less than, or slightly greater than,the natural height H_(N) (FIG. 2C); in any event, the restored heightH_(R) will be greater than the fractured height H_(F) (FIG. 2C).

Returning to FIG. 3A, the second cavity-forming device 20 b is thenoperated to transition the second working end/balloon 62 b from theexpanded state to the contracted state (e.g., the second balloon 62 b isdeflated). In the contracted state of the second working end/balloon 62b, the second cavity-forming device 20 b may be removed from the secondcannula 22 b.

Other embodiments of a system and method for bone augmentation aredescribed with reference to FIGS. 4A-4H. A system 410 is illustrated inFIG. 4A that may be similar or identical in most respects to the system10 described above, and corresponding reference numbers should beunderstood as analogous. Those of skill in the art will appreciate thatsystem components described above with reference to FIGS. 1-3B and inthe various incorporated references may be used with the embodimentsdescribed below within the scope of the present disclosure. The systemincludes an access cannula 422 (preferably generally straightline inconfiguration), which is shown as engaged into a cancellousbone-including region 508 (that may also include marrow and other bodymaterial as noted above with reference to FIGS. 2A-3B) of a vertebra 500via a vertebral pedicle 502 thereof. The distal end 442 of the accesscannula 422 has been directed near a target region/site 520 that isgenerally central within the bone region 508. A portion of the boneregion 508 may be at least partially defined by a cortical rim 506forming a boundary of the anterior vertebral body 504.

The target site 520 may be identified by a physician preparing for avertebroplasty procedure or other bone-augmentation procedure asdiscussed herein. Identification of the target site may includegenerally determining a central location in the cancellous bone portionof the vertebra 500 that will substantially or at least generallysupport height-restoration and/or structural augmentation thatpreferably is at least generally symmetrical with respect to thevertebra and particularly with respect to damaged portion(s) thereof.Generally, the target site may be approximately centered within the bonestructure. However, the target site is defined more generally as apre-determined location within a bone structure that may be determinedby treating personnel to provide for symmetrical application of force totreat a bone in one or more locations within the bone determined to bemost beneficial for the patient.

As shown in FIG. 4B, a stylet 470 may be directed through the accesscannula 422. The stylet 470 snugly but slidably extends through anoverlying delivery tube 417 that preferably is made a flexible polymerhaving some columnar strength (e.g., polypropylene, PEEK) that willmaintain a patent longitudinal lumen upon withdrawal therefrom of thestylet 470. As used herein, “overlying” will be understood by those ofskill in the art to describe a coaxial arrangement of the delivery tube417 around the stylet 470 whereby they may simultaneously be movedlongitudinally (e.g., to a target site) while remaining coaxially andlongitudinally aligned, whereafter the stylet 470 may be withdrawn froman inner delivery tube lumen defined/bordered/encompassed by theflexible polymeric delivery tube 417. The term “flexible” as used hereinwill be understood in context by those of skill in the art in describingthe delivery tube 417 as being able readily and without crimping orcollapsing to assume the curvatures shown and described herein. Thedelivery tube 417 may include at least one radio-opaque marker (e.g.,near its distal end) and/or one or more visual indicia near its proximalend providing for user-observation regarding its distal end positionrelative to the access cannula of the system. The at least oneradio-opaque marker includes that the delivery tube may itself bepartially or wholly radiopaque. For example, in certain preferredembodiments, a PEEK (or other polymer) delivery tube 417 may be extrudedor otherwise manufactured with Barium in it, such that some or all ofthe entire tube is radiopaque, obviating the need for other radio-opaqueindicia.

The stylet 470 preferably is constructed including a memory metalmaterial having a pre-set curve near its distal end. In this manner, thestylet 470 can be deflected to a generally straight orientation while itis being directed through the access cannula 422. The stylet 470 and theoverlying flexible polymeric delivery tube 417 have sufficient length toextend through and be operable beyond the distal end 442 of the accesscannula. Thus, as shown in FIG. 4B, in the time and space that thestylet 470 is advanced out of the distal end 442 of the access cannula422, its pre-set curve is re-asserted such that the stylet 470 andoverlying delivery tube 417 curve as they are advanced into the targetregion 520. The pre-set curve of the stylet 470 may be offset from itsdistal end sufficiently to provide a generally straightline portion ofthe stylet distal of its pre-set curve. A proximal-end structure of thestylet 470 may include indicia 471 showing the direction of curvature ofthe pre-set curve (FIG. 4C).

In certain embodiments, a system may include a plurality of stylets,each having a different pre-set curve. In this manner, a physician maydetermine a desirable stylet curvature to reach the target region via,for example, one or more transpedicular access sites and select anappropriate stylet. Each stylet may be individually packaged and clearlymarked with size and/or curvature, as well as providing other visualindicia of properties of interest to a physician. In use, the physicianmay determine a desired curvature path between the distal end 442 of theaccess cannula and the approximate center of the target site (e.g., inthe middle of the pre-determined location, which may or may not begenerally centered within a bone portion), select a guide styletincluding a distal preset curve corresponding to said curvature pathfrom a plurality of guide stylets having different preset curvatures,and insert the selected stylet through the delivery tube 417 beforedirecting the assembled stylet and the then-overlying tube 417 to thetarget site.

As shown in FIG. 4C, the stylet 470 may be withdrawn from the deliverytube 417 (which is shown as slightly retracted from its furthestextension point) after having created a curved generally tubular path orvoid 521 in the material 508 in the target region 520. Thereafter, asshown in FIG. 4D, a cavity-forming device, which may include a workingend embodied as—for example—a distal balloon 462, may be directed intothe path 521 formed by the stylet 470 and now lined by the delivery tube417 that was formerly overlying the stylet 470 before the stylet waswithdrawn. The cavity-forming device(s) may include components analogousto or substantially like those shown in FIG. 1 and discussed withreference to its embodiment including devices 20 a and 20 b, althoughthe devices shown in the embodiments of FIGS. 4C and following primarilyshow only an expandable member portion such as a balloon and will beunderstood to have a more flexible inflation-path-shaft than shown for20 a/20 b. A wire or other support structure (not shown) may be providedin the cavity-forming device end 462 to enhance its trackability andpushability through/into the path 521. As a point of reference, FIG. 4Eprovides a lateral view of the vertebral body 504 wherein the workingend/balloon 462 has been deployed (and is still in a contracted state).As shown, the vertebral body 504 being treated is anteriorly fractured(referenced generally at 522) and thus exhibits a fractured height H_(F)that is less than a natural or native height H_(N) (designatedgenerally).

In one preferred embodiment of a method, the delivery tube 417 may beextended all the way to the end of the cavity/void formed with thestylet 470. Thereafter, the cavity-forming device may be extendedthrough the delivery tube 417 until its working end/balloon 462 contactsthe bone at the distal end thereof. This may protect, e.g., a balloon orother distal expandable member of the cavity-forming device fromexternal damage during introductory movement and provide for itsplacement in a desired location and orientation. In other words, thedelivery tube will preferably effectively prevent the balloon fromdamaging contact (e.g., puncture, cut, tear, or other damage) with andcaused by bone structure along the path to the target site. Thereafter,the delivery tube 417 may be withdrawn sufficiently to allowcavity-forming expansion of the working end/balloon 462 as describedbelow. Those of skill in the art will appreciate that one or more of thecavity-forming device, working end/balloon 462 thereof, and the deliverytube may include visual indicia (e.g., markings on the user-held end,radio-opaque indicia at or near the distal end) that enable a user todetermine the relative positions of those components to perform a methodas described. In this or other embodiments, the inner diameter of thedelivery tube 417 and/or the external surface(s) of the cavity formingdevice(s) may be lubriciously coated (e.g., with silicone, PTFE, and/oranother lubricious material).

With reference to FIG. 4F, the cavity-forming device may be operated tocause its corresponding working end/balloon 462 to form a (preferablyapproximately, generally, or substantially centered) cavity/void in thebody material 508. For example, the working end/balloon 462 may beexpanded (e.g., inflated). As best illustrated in FIG. 4G, expansion ofthe working end/balloon 462 not only forms the cavity, but may alsorestore or enhance a height of the fractured vertebral body 504. Moreparticularly, a restored height H_(R) is established that maybeneficially approximate the natural height H_(N). Such a restoredheight H_(R) may be the same as, slightly less than, or slightly greaterthan, the natural height H_(N) (FIG. 4E); in any event, any restoredheight H_(R) will be greater than the fractured height H_(F) (FIG. 4E).If desired for fluoroscopic visualization, radio-opaque contrastmaterial may be provided into the cavity, internal to or external of theexpandable member. Transpedicular access for kyphoplasty at a targetsite approximately centered in the cancellous bone may not be easilyachievable without the curved stylet approach of the present disclosure.The limits of patient anatomy, the desirability of minimizing proceduretime (for the sake of, e.g., cost and patient health), and thedesirability of minimizing patient recovery time all provide foradvantages of the present methods and systems.

Thereafter, the expandable member's working end/balloon 462 may bewithdrawn. Then, as shown in FIG. 4H, curable material 530 may bedelivered into the cavity via the delivery tube 417. In this or otherembodiments, the curable material may delivered in a more targetedmanner via a curved delivery cannula 426 (e.g., as shown in FIG. 4I)directed though the access cannula into the cavity 521 (as shown in FIG.4J). In such an embodiment, the delivery tube 417 may be removed as anintermediate step before introducing the curved delivery cannula 426.Methods and devices for use in introducing curable material via a curveddelivery cannula in a manner useful within the presently disclosedsystems and methods are disclosed in U.S. Pat. Nos. 7,713,273;7,799,035, and 8,128,633, as well as U.S. Pat. App. Publ. Nos.2010/0087828 and 2011/0112588, each of which is incorporated herein byreference in its entirety. It should be understood and appreciated thatthe “delivery cannula” described therein may include a pre-set curvewith structure and function of the curve described herein in referenceto a “stylet.” However, the term “stylet” as used herein is defined toexclude a delivery cannula that has an internal lumen dimensioned andoriented for delivering curable material, whereas the “stylet” isspecifically configured and dimensioned for providing a structurecoaxially over/around and along which another device may longitudinallybe directed. This definition may, in some embodiments, allow for astylet that includes a lumen while excluding a stylet lumen in otherembodiments, where a typical preferred embodiment will include a styletwith a generally solid cross-section and no continuous longitudinallumen. It should also be appreciated that the present disclosure enablesone of skill in the art to execute the methods of FIGS. 4A-4H inmultiple within a single bone structure: i.e., using overlying deliverytube(s) 417 the methods and structures described after the initialset-up shown in FIG. 2A.

In certain embodiments, a delivery cannula may be provided withtemperature-dependent multi-curve structure and function as shown anddescribed in commonly-owned U.S. Pat. No. 8,699,884 (alreadyincorporated herein by reference). This cannula may further include anoverlying delivery tube 417 and be operated in the manner describedabove for a stylet, except that the curable material may be introducedthrough the delivery cannula (e.g., after it is withdrawn; theexpandable member is introduced, activated, and withdrawn on its own orwith the tube 417; then the delivery cannula—potentially pre-loaded withcurable material—is reintroduced through the passage originally createdby the stylet).

In some embodiments, which will readily be appreciated by those of skillin the art with reference to the present disclosure and materialsincorporated herein by reference, a delivery cannula (e.g., withreference to delivery cannula 426 of FIGS. 4I-4J) may include a closeddistal end terminus 491 and a side-facing opening 493 near the terminus491, where the opening is oriented along an outside surface of thecurved portion 495 of the delivery cannula near its closed distal endterminus. It may also include proximal-end indicia 497 that show thedirection of distal cannula curvature. The curvature of the deliverycannula may be configured to correspond to the pre-set curve of thestylet 470. In some embodiments, the delivery cannula may be pre-loadedwith curable material before the delivery cannula is directed throughthe guide cannula, in order to decrease procedure time and reduce thelikelihood of a bolus during introduction of the curable material.

Those of skill in the art will appreciate that embodiments not expresslyillustrated herein may be practiced within the scope of the claims,including that features described herein for different embodiments maybe combined with each other and/or with currently-known orfuture-developed technologies while remaining within the scope of theclaims. Although specific terms are employed herein, they are used in ageneric and descriptive sense only and not for purposes of limitation.It is therefore intended that the foregoing detailed description beregarded as illustrative rather than limiting. And, it should beunderstood that the following claims, including all equivalents, areintended to define the spirit and scope of this invention. Furthermore,the advantages described above are not necessarily the only advantagesof the invention, and it is not necessarily expected that all of thedescribed advantages will be achieved with every embodiment. In theevent of any inconsistent disclosure or definition from the presentapplication conflicting with any document incorporated by reference, thedisclosure or definition herein shall be deemed to prevail.

We claim:
 1. A method for stabilizing a bone structure of a patient, themethod comprising steps of: identifying a target site for locating anexpandable member within a bone structure at a predetermined location,directing a distal end of a generally straight access cannula into thebone structure near the target site; providing a guide stylet assemblythat comprises a stylet including memory metal and having a distalpre-set stylet curved portion; and an overlying flexible polymericdelivery tube through which the stylet snugly and slidably extends,where the stylet and the delivery tube have sufficient length to extendthrough and be operable beyond the distal end of the access cannula, andwhere the pre-set curved portion is held generally longitudinallystraight when the stylet is constrained by the access cannula; directingthe stylet and overlying delivery tube simultaneously and coaxiallythrough the access cannula and out the distal end of the access cannula,where the pre-set stylet curved portion, no longer constrained by theaccess cannula, curves toward and forms a path into the target site asit is extended out of the access cannula distal end; withdrawing thestylet from the overlying delivery tube; thereafter removing thedelivery tube; directing a coated expandable member in a contractedstate via the access cannula into the target site; expanding theexpandable member to form a cavity at the target site; and, thereafter,delivering a curable material into the cavity.
 2. The method of claim 1,further comprising, executing steps of: as part of the step of directinga distal end of a generally straight access cannula into the bonestructure near the target site, determining a desired curvature pathbetween the distal end of the access cannula and the approximate centerof the target site; where the desired curvature path is determined bythe curvature of the distal preset curved portion; and where the step ofdirecting a distal end of a generally straight access cannula into thebone structure near the target site includes desirably locating andorienting the generally straight access cannula so that, during the stepof directing the stylet and overlying delivery tube includes directing adistal end of the stylet and overlying delivery tube to an approximatecenter of the target site.
 3. The method of claim 1, where the accesscannula is located and oriented relative to the target site so that thepre-set curved portion of the stylet is oriented to transit from thedistal end of the access cannula to approximately the center of thetarget site.
 4. The method of claim 1, where the cavity formed isgenerally symmetrical within the target site.
 5. The method of claim 1,where the cavity formed is generally symmetrical within the bonestructure relative to boundaries of the bone structure.
 6. The method ofclaim 1, further comprising, before the step of delivering curablematerial, removing the expandable member.
 7. The method of claim 1,where the step of delivering curable material into the cavity comprisesdirecting a curved delivery cannula through the access cannula into thecavity and directing curable material through the curved deliverycannula into the cavity.
 8. The method of claim 1, where the expandablemember comprises a silicone-coated balloon.
 9. The method of claim 1,where the curable material is delivered through a delivery tube that maybe the same or different than the removed delivery tube.
 10. The methodof claim 1, where the delivery tube comprises at least one radio-opaquemarker.
 11. The method of claim 1, where the step of delivering curablematerial into the cavity comprises directing a curved delivery cannulathrough the access cannula into the cavity and directing curablematerial through the curved delivery cannula into the cavity, where thedelivery cannula curvature is temperature-dependent.
 12. The method ofclaim 1, where the step of delivering curable material into the cavitycomprises directing a curved delivery cannula through the access cannulainto the cavity and directing curable material through the curveddelivery cannula into the cavity, and where the curvature of the curveddelivery cannula is about the same as the curvature of the pre-setstylet curved portion.
 13. The method of claim 1, further includingproviding radio-opaque contrast material into the cavity, internal to orexternal of the expandable member.
 14. The method of claim 1, where thestylet includes a distalmost straight length that is distal of thepreset curved portion.
 15. A system configured for stabilizing a bonestructure of a patient, the system comprising: an access cannulaconfigured for penetrating into a bone structure; a guide styletassembly that comprises a stylet including a distal memory metal pre-setcurved portion; and an overlying flexible polymeric delivery tubethrough which the stylet coaxially, snugly, and slidably extends, wherethe stylet and the delivery tube have sufficient length to extendthrough and be operable beyond the distal end of the access cannula, andwhere the pre-set curved portion is held generally longitudinallystraight when the stylet is constrained by the access cannula; asilicone-coated expandable member dimensioned and operable for passagethrough and deployment outside a distal end of the delivery tube in amanner displacing bone material; and a curved delivery cannulaconfigured for delivering curable material into a bone.
 16. The systemof claim 15, where the delivery cannula includes a closed distal endterminus and a side-facing opening near the terminus, where the openingis oriented along an outside surface of the curved portion of thedelivery cannula near the closed distal end terminus.
 17. The system ofclaim 16, further comprising proximal end indicia showing the directionof curvature of the curved delivery cannula.
 18. The system of claim 15,further comprising proximal end indicia showing the direction ofcurvature of the stylet's pre-set curve and indicating when a distal endterminus of the stylet is aligned with and ready to exit the distal endof the delivery tube.
 19. The system of claim 15, where the expandablemember is embodied as a fluid-inflatable balloon configured to create acavity by displacing cancellous bone.
 20. The system of claim 15,further comprising a curved delivery cannula configured for passagethrough the access cannula and including a pre-set curved portioncorresponding to the curvature of the stylet pre-curved portion, thedelivery cannula containing pre-loaded, but not-yet-cured, curablematerial.